You would need someone thoroughly familiar with California's arcane laws, but at a quick reading it seems the Church already needs a PSE license. As long as they aren't providing security services to any other business or entity I don't see where a PPO license would be required (but Kalifornia has some weird laws, it is always best to consult a local lawyer then double check even their answer)
Im in Indiana and im very active in the church security team. The local Sheriffs Dep. came into give us a few pointers and about legal obligations. Anyone who wants to join the safety team must fill out a form that is given to the police department (for safety in case of a shooing, police will know who is legally armed). We are also raising standards to join: you have to be able to shoot well. A low standard would be 8in groups at 7 yards, but that is not set yet. That is still in planning. Hope this helps.